Patent document 1 discloses a switch apparatus used in an engine starting system for a vehicle. The user of the vehicle, to which the above system is applied, carries an electronic key (referred to as portable device) instead of a conventional mechanical key. When the electronic key is verified and an affirmative determination is made that the electronic key is the key for the vehicle, the vehicle enables vehicle control such as starting of the engine. More specifically, the portable device incorporates a battery and transmits identification information (ID) that is unique to the portable device in response to a request signal from the vehicle. The vehicle determines whether or not the ID obtained from the portable device conforms to a reference ID. Under the condition that the ID obtained from the portable device conforms to the reference ID, the vehicle enables vehicle control. Thus, when the user operates a knob of the switch apparatus located near the driver seat while carrying the portable device, the engine can be started.
However, when the voltage of the battery incorporated in the portable device is low, the portable device cannot transmit the ID in response to the request signal. Thus, in this case, even when the user operates the knob of the switch apparatus while carrying the portable device, the engine cannot be started. In the above system, the switch apparatus generally includes an antenna coil to cope with a situation such as battery depletion. Operation of the knob of the switch apparatus triggers transmission of a drive radio wave from the antenna coil. When entering a transmission area of the drive radio wave, the portable device generates power from the drive radio wave and transmits the ID with the generated power. Thus, when the user operates the knob of the switch apparatus while holding the portable device near the switch apparatus, the engine can be started. The switch apparatus that is capable of performing a communication operation with the antenna coil and a switch operation with the knob as described above is referred to as a switch apparatus having a wireless function.
Referring to FIG. 8, a switch apparatus 51 having a wireless function includes a case (not shown). The case accommodates a board 52 on which necessary components are mounted. The mounted components of the board 52 include an antenna unit. The antenna unit includes a bobbin 53, an antenna coil 54, which is wound around the bobbin 53, and a terminal 55, which is located on the bobbin 53. The terminal 55 includes a first end portion and a second end portion, which project from the bobbin 53. One end of the antenna coil 54 is wound around the distal end of the first end portion of the terminal 55. The antenna coil 54 and the terminal 55 are joined together through swaging or the like. The distal end of the second end portion of the terminal 55 is inserted into a hole of the board 52. The part of the second end portion of the terminal 55 passed through the hole is soldered to an upper surface of the board 52.
Additionally, a terminal 57 of a connector 56, which is one of the mounted components, is soldered to the board 52 at a location separated from where the terminal 55 is soldered. The terminal 57 of the connector 56 is electrically connected to the terminal 55 of the antenna coil 54 by a conductive pattern of the board 52. In addition to the terminal 57, the connector 56 includes a terminal that functions as a medium for outputting a switch signal corresponding to the operation of a knob (not shown) or the like to an external apparatus. This enables the switch apparatus 51 having a wireless function to exchange electric signals with the external apparatus. The communication operation and the switch operation are reflected on the vehicle control.